No it doesn’t. Muscle cannot convert to fat. When you stop exercising then muscles will diminish in size, generally lowering your metabolic rate. The drop in kJs/Calories burned through less exercise and a lower metabolism makes it so much easier to gain kilos as fat. Muscles start to shrink after four decades on the planet, so it is a great idea to keep active through life so that you both maintain your muscle mass and keep your metabolic rate up. That applies to both men and women, especially those that enjoy their chocolate.